Composite grating structure



June 21, 1960 H. NAGIN 2,941,455

COMPOSITE GRATING STRUCTURE Filed Nov. 29. 1954 INVENTOR. Harold Nagin ATTORNEYS United States Patent 2,941,455 COMPOSITE GRATING STRUCTURE Harold Nagin, Pittsburgh, Pa., assignor to Reliance Steel Products Company, McKeesport, Pa., a corporation of Pennsylvania Filed Nov. 29, 1954, Ser. No. 471,666

2 Claims, (Cl.

This invention is for a new composite grating such as those used in bridge floors and other trafiic bearing surfaces, as well as platforms, sidewalks and elsewhere.

Gratings of the type referred to are generally comprised of one set of parallel main bars or sections of metal called bearer bars, and another set of transversely extending bars, called cross bars. The cross bars are pressure welded or otherwise secured to the bearer bars and the tops of the two sets of bars are in the same plane.

One "objection to gratings of this character, especially when used for vehicular traflic, is that skidding may occur, due to the metal having a low coeflicient of fric- "tion when wet, and another is that the edges of the metal bars provide a relatively small surface on which the wheel of the vehicle rests, causing excessive vibration.

In my copending application Serial No. 456,380, filed September 16, 1954, now Patent No. 2,895,389, I have shown a grating designed to provide an improved traction surface by having a relatively thin coating of abrasive grains secured over the tread surface by an epoxy .zresin.

Such a mixture will adhere firmly to the metal, even under heavy traflic. 7

An object of the present invention is to provide an improved grating in which both sets of bars has the top edge of each bar provided with a trough-like formation into which a filling of resin and abrasive mix is placed, the filling preferably being heaped to a level above the tops of the troughs. This provides a greater mass of the resin abrasive material to resist wear than does the grating of my copending application above referred to. It further provides a grating which presents wider traction surfaces to the wheels of vehicles, or in the case of sidewalk gratings, to the shoes of the wearer.

A further object of the invention is to provide a new form of composite grating formed principally of metal, but having the wearing surface provided of firmly anchored abrasive and resin material having a high coefiicient of friction.

My invention may be more fully understood by reference to the accompanying drawings, in which:

Fig. 1 is a plan view of a grating embodying my invention;

Fig. 2 is a longitudinal section in the plane of line 11-11 of Fig. 1;

Fig. 3 is a transverse section in the plane of line HI- IU of Fig. 1;

Figs. 4 and 5 are transverse sections on a larger scale through the individual bearer and cross bars respectively of the grating shown in Fig. 1.

The grating as disclosed in the drawings is comprised of main bearer bars 6 and transversely-extending cro'ss bars 8. The main bearer bars 6 are of substantially deeper section than the cross bars 8, and except at the top they are of solid section as is common in gratings of this type. The top edges of the main bearer bars are rolled in such manner as to provide upwardly-diverging flanges, forming between them a trough 7. The cross bars 8 have their top edges similarly formed to provide troughs 9. As

of the respective bars are filled with a resin-abrasive composition to a level extending above the level of the edges of the trough so that the resin-abrasive composition extends continuously throughout the full length of the grooves of both the cross bars and the main bearer bars, and this condition exists at the intersections of the cross bars and the main bearer bars as well as elsewhere in the length of the bars, as is clearly shown in the drawings. The filling extends upwardly above the edges of the troughs in both sets of bars to a substantially common level and provides the entire traflic-bearing surface of the grating. The resin-abrasive mix provides a tough wearresistant surface having a high coefiicient of friction and the resin used has a strong adhesion to metal under all temperature conditions to which a grating of this character would be normally subjected, and will not creep or flow.

The resin-abrasive composition may be any of the various compounds described in my application Serial No. 456,380, filed September 16, 1954, now Patent No. 2,895,389, of which the present application is an improvement, or disclosed in the application of Harry 'S. Nagin and Dona ld ll Russell, Serial No. 427,873, filed May 5, 1954, in both of which the resin is ,comprised'in substantial part or entirely of an epoxy resin and the abrasive is ,a particulate or granular material such as grains of aluminum oxide or other abrasive, sand, or an abrasive in conjunction with sand, or sand with hydraulic cement.

ciously to m'e'tal-over all temperature conditions to'which a grating is normally subjected in use, neither becoming excessively brittle when very cold, nor softening when exposed to hot sunshine. They are the reaction products of epichlorohydrin and diphenylolpropane, and are available as liquids, semi-liquids, and solids. In the practice of the present invention I prefer to use an epoxy resin having a light syrupy consistency at room temperatures. To cure these resins, it is necessary to use a catalyst which is introduced at the time that the resin-abrasive composition is prepared, and which remains in the cured resin. Catalysts for the resin are in the class of polyamines, as diethylene triamine, ethylene diamine, dimethylpropyl amine, diethylamino-propyl amine, piperidine and pyridine, and are well known in the art. Different catalysts may affect the temperature required to cure the resin, and the amount of catalyst will also vary the curing time. I have found diethylene triamine to be satisfactory in the ratio of about 10% by Weight of catalyst to resin. Sorne resiliency without loss of adhesive qualities may be imparted to the epoxy resins and some economy effected by adding thereto natural or synthetic rubber, either in the granulated form or the latex form. Thus polyvinyl acetate latex, natural rubber latex, and latex or emulsion forms of synthetic rubbers may be added to the mix. For instance, a mixture in the approximate proportion by weight of one pound of commercial epoxy resin of a light syrup like consistency to 2.5 ounces of catalyst to 3.5 ounces of rubber or latex as above described may be used. When polyvinyl acetate latex is used, it is one commercially available having a resin content of about 50% to 50% of water.

Another example is one part by volume of Epon No. 828 resin plus 10% by weight of catalyst with 10 parts by volume of sand or harder abrasive grains such as aluminum oxide, silicon carbide, or crushed natural rock particles. The mix used should be a relatively stifi mix which is capable of being heaped into the trough and retaining its form, although it need not have exactly the percentages above indicated. Also various mixes includ ing epoxy resin with or without polyvinyl acetate with hydraulic cement and abrasive grains as disclosed in the aforementioned application of Nagin and Russell may be employed with not less thanabout 50% of the total resin being an epoxy resin. -For example I may prepare an emulsion of epoxy resin of the character described and polyvinyl acetate latex with about equal weights of the two resin solids, and with it diethylene triamine as a catalysausing about by Weight of catalyst to epoxy resin content. I add one part of.

,quick setting cement or Portland cement to .1 to .15 part ;by weight of resin solids. other aggregate or combinations ot sand and other aggregate, such as abrasive grains to form a, stiff mixgtherc To this mix is addedsand or being from 3 to Sparts ofsand and/pr aggregate to 1 part ofcement. Water may be added as needed. The

same formula may be followedusing only epoxy resin emulsion instead of the two resins. A substantial pro portion of the resin must be an epoxy resin in order to secure high adhesion of the mix to the metal; when it solidifies. H a,

The composition per se forms no part of myinvention which is directed to a grating havingtrough-like surfaces in some or all portions of the tread surface thereof into which the resin-abrasive composition having the desired characteristics is filled and hardened or cured, s

I claim: v p 1. A composite metal grating comprised of a series of parallel main bearer bars of solid section, a series of cross bars ofsolid section intersecting the main bearer bars and set into the top edges ofv the main bearer bars and of less depth than the main bearer bars, the top edges of both series of bars being in a common plane, the top edges of both series of bars having oppositely flared sides defining a V-shaped trough and having an overall width greater than the transverse thickness of the bars, and a filling in the aforesaid troughs, the filling being comprised of a thermosetting epoxy resin and hard abrasive grains cured in situ in the trough whereby the resin is bonded to the metal and to the grains, said filling projecting above the upper edges of said troughs and covering the intersections, the filling constituting the entire trafiic bearing surface of the grating. V

2. A composite metal grating comprised of a series of parallel main bear-er bars, a series of cross bars intersecting the main bearer bars and set into the top .edges of the main bearer bars and of less' depth than the main bearer bars, the top edges of both series of bars being in a common plane, the top edges of both series of bars having oppositely flared sides defining a V-shaped trough, and a filling in the aforesaid troughs, the filling being composed of a thermosetting epoxy resin and hard abrasive grains cured in situ in the troughs whereby the resin is bonded to the metal and to the grains, said filling pro- 'jecting above the upper edges of said troughs and covering the intersections, the filling constituting the entire tratfic-tbearing surface of the grating.

References Cited in the file of this patent UNITED STATES PATENTS 513,453 Great Britain Oct. 12, 1959 

